Subbing photographic paper supports



Oct. 10, 1944. M. F. FILLIUS 2,350,216 SUBBING PHOTOGRAPHIG PAPER SUPPORTS Filed June 8, 1943 FIG. 1.

13 EMULSION 12 GELATIN AND ACRYLATE REYSIN SUB. 11 ACRYLATE. RESIN 10 "\PAPER SUPPORT '11 \ACRYLATE RESIN FIG. 2 13 15 EMULSION HIGH GELATIN AND LOW ACRYLATE RESIN sue LOW GELATIN AND HIGH ACRYLATE RESIN sue A ACRYLATE RESIN PAPER SUPPORT CRYLATE RESIN MILTON F; FILLIUS INVENTOR WW G8 MZM ATTORNEYS Patented a. 10, 1944 SUBBING PHOTOGRAPHIC PAPER SUPPORTS Milton F.. Fillius, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application June 8, 1943, Serial No. 490,039

6 Claims.

This invention relates to water-resistant photographic paper and to a method for subbing such paper.

In Bryce and Staehle U. S. application Serial No. 490,050, filed concurrently herewith, there is described a method for coating photographic paper with acrylate resins to render the paper moisture-resistant so, that the paper does not absorb a large amount of water or chemicals during processing or during storage in changing atmospheric conditions. I have found that when a sensitive gelatin emulsion is coated on such resin coated paper the emulsion does not adhere well when the paper is wet, as during photographic processing.

It is, accordingly, an object of the present invention to provide a method for subbing resin coated photographic paper. A further object is toprovide a method for preventing wet stripping of a photographic emulsion from resin coated photographic paper:

These objects are accomplished, according to my invention, by'subbing the resin coated paper with a mixture of an acrylate resin and gelatin.

In the accompanying drawing, Fig. 1 is a sectional view of a resin coated paper having a single subbing layer according to my invention.

Fig. 2 is a sectional view of a resin coated paper late coated sheet will adhere fairly well when 1 dry, but when wetted will separate from the acrylate coating. To overcome this, it is necessary to coat the acrylate coated sheet with a primer or sub and, for this purpose I have found that a mixture of the acrylate suspension and a gelatin solution to which formaldehyde or a chromium salt has been added works very well. The ratio of gelatin to acrylate which gives the most satisfactory result, varies depending upon the hardness of the acrylate used. I have found in practice that ratios varying from one part of gelatin in from /2 to 8 parts of acrylate resin is satisfactory. The use of the gelatin hardening agents mentioned above is optional since good results can be obtained in the absence of these agents.

The adhesion of the final sensitive emulsion can be increased even further by the use of several subbing layers, in which the ratio of gelatin to acrylate is successively increased. This gradually changes the nature of the materialv from a 100% acrylate phase through several difierent ratios of the two common phases to a phase in which the adhesive material is 100% gelatin.

It has also been found that increased adhesion of the final photographic emulsion to the sup- In the accompanying drawing, Fig. 1 illustrates a resin coated paper subbed according to my invention. As shown therein the support I0 is coated on both sides with layers llv of an acrylate resin in the mariner described in the Bryce and Staehle application Serial No. 490,050.

ing on the rear surface of the support may contain a wax as described in Vogel U. S. application Serial No. 490,049, filed concurrently herewith. One of the acrylate layers is coated with a subbing layer I2 of a dispersion of acrylate resin containing gelatin. After drying, this layer is coated with the usual gelatino-silver halide emulsion layer l3.

Fig. 2 illustrates another modification of my invention inwhich the paper support I0 is coated 'with the acrylate resin layers II and one of these layers is coated with successive subbing layers [4 and IS. The layer I4 contains a low amount of gelatin and a high amount of acrylate resin and the layer 15 contains a high amount of gelatin and a low amount of acrylate resin. The sensitive emulsion layer I3 is then coated on layer I5. In'this way the gelatin content of the successive layers is increased from the support outward so that good adhesion of the layers is obtained during and after photographic processing. It will be apparent that more than two subbing layers may be applied, the proportion of gelatinto resin increasing in the successive layers.

My invention will be further illustrated by reference to the following specific examples.

Example 1 A baryta-coated paper was coated on the baryta side with an aqueous dispersion of a, polyacrylate resin containing 25% resin. On the opposite side of the paper wa coated an aqueous dispersion of a mixture of equal parts of a 25% aqueous dispersionof a polyacrylate resin and a 15% aqueous dispersion of carnauba wax. Over the first coating was applied; a sub from a water system containing 3.5 parts of gelatin and 10 parts of polyacrylate resin insuspension. When dry, this The coatgave a layer containing three parts of acrylate resin and one part of gelatin. Over this was applied a sensitive gelatino-silver halide emulsion.

Example 2 Baryta-coated paper was coated on one side with a dispersion of a mixture of three parts of 25% vpolyacrylate resin dispersion and one part of 15% 'carnauba wax dispersion. After drying,

the opposite side of the-paper was coated with a' 25% aqueous dispersion of a polyacrylate resin followed by a gelatin-resin sub-containing polyacrylate resin and 3.5% gelatin which on drying, gave'a layer containing three parts of resin and one part of gelatin. This was followed by the usual photographic emulsion layer.

Example 3 Baryta-coated paper was coated on both sides with a 25% aqueous dispersion of a polyacrylate resin and the baryta side of the paper was then coated with a subbing layer from a dispersion of a mixture of one part of 3% gelatin solution and one part of 6% aqueous dispersion of a polyacrylate resin followed by the emulsion layer.

- Example 4 Baryta-coated paper was coated on the rear surface with two separate layers each coated from a dispersion containing 3 parts of 25% aqueous dispersion of a polyacrylate resin and one part of a aqueous-dispersion of carnauba wax. On the baryta side was, coated a aqueous dispersion of a polyacrylate resin followed by '9. subbing layer coated from a mixture .of one part of 8% polyacrylate resin dispersion and one part of 2% gelatin solution; followed by the emulsion layer.

' Example 5 Baryta-coated paper was coated on both sides of a 25% aqueous dispersion of'a polyacrylate resin and on the baryta side with a mixture of equal parts of 4% gelatin solution and a 5% aqueous dispersion of a polyacrylate resin. The latter coating was dried and coated with the usual sensitive emulsion layer. 4

Example 6.

. a photographic emulsion. Tests showed the paper to be highly water-resistant and satisfactory with respect to wet and dry adhesion.

Example 7 vA baryta-coated paper base was coated on the rear surface with a 25% aqueous dispersion of a medium hardness acrylate resin to which one part of carnauba wax had been added. The baryta-' coated surface was coated with a 25% aqueous dispersion of a medium hardness acrylate resin followed by a subbing layer-of adispersion of three parts of a soft polyacrylate resin to one part of gelatin. The paper was then coated with various photographic emulsions to which different amounts .of a soft polyacrylate resin had been added. Three coatings were made in which the ratio of acrylate resin to gelatin varied as follows: 1 to 4, 1 to 2 and 2 to 3. In all cases good, wet and dry adhesion and satisfactory water-resistance were obtained. v

The acrylate resin used in the preparation of the sub according to my invention may consist of the polymerization product of any of the usual acrylates well known in the industry such as acrylic acid, methyl acrylate, ethyl acrylate, acrylic acid nitrile, or mixtures of these in any proportions. I may use an aqueous dispersion such as that sold by the Rohm & Haas Chemical Corporation of Philadelphia, Pa., under .the name Rhoplex W-66, which is believed to be a dispersion in water of a resin consisting principally of polymethyl acrylate'and containing about 25% resin.

It will be understood that the examples and modifications included herein are illustrative only and that my invention is to be taken as limited only by the scope of the appended claims.

I claim:

1. A light-sensitive photographic element having a water-resistant support, comprising a paper base coated on both sides thereof with a waterresistant acrylate resin, at least one of said acrylate resin layers being coated with a subbing layer comprising a mixture of an acrylate resin and gelatin, followed by a sensitive photographic emulsion layer.

2. A light-sensitive photographic. element having a water-resistant support comprising a paper base coated on both sides thereof with a waterresistant acrylate resin, one of said acrylate resin layers being coated with at least two subbing layers comprising a mixture of an acrylate resin and gelatin, the proportion of gelatin to resin being successively increased in the layers farth est from the paper base, and the subbing layers being followed by a sensitive photographic emulsion layer.

3. A light-sensitive photographic element havinga water-resistant support comprisin a paper base coated on both sides thereof with a waterresistant acrylate resin, one of said acrylate resin layers being coated with a mixture of a subbing layer of acrylic acid ester resin and hardened gelatin, said subbing layer being coated with a sensitive photographic emulsion layer.

- 4. A light-sensitive photographic element having a water-resistant support comprising a paper base coated on both sides thereof with a waterresistant acrylate resin, one of said acrylate resin layers being coated with a subbing layer comprising a mixture of an acrylate resin and hardened gelatin, the ratio of gelatin to acrylate resin varying from one part of gelatin in from to 8 parts of acrylate resin, said subbing layer being coated with a sensitive photographic emulsiongelatin, dryingthe 'coating thus formed, and" applying thereto a sensitive gelatin emulsion layer.

MILTON F. FILLIUS. 

